A liquid crystal panel, which is an element of a liquid crystal display device, has a structure in which a pair of substrates face each other while a prescribed gap is securely kept between the substrates. In the gap between the substrates, a liquid crystal layer containing liquid crystal molecules is enclosed. On surfaces of the substrates which are in contact with the liquid crystal layer, alignment films for regulating the alignment state of the liquid crystal molecules are formed (for example, Patent Document 1, etc.).
In such an alignment film, a pinhole may possibly be made locally for the following reasons.
(1) The alignment film has foreign substances mixed therein during the film formation process. By removal of the foreign substances, the alignment film is locally cut away and thus a pinhole is made.
(2) The adhesiveness of the alignment film to an underlayer (pixel electrodes, counter electrode, etc.) is locally poor and the alignment film material is repelled at such a portion during the film formation process, and thus a pinhole is made.
(3) In the case where an alignment film material for vertically aligning the liquid crystal molecules is used, the adhesiveness of the alignment film to the underlayer tends to be poor. This, together with the reason (2) above, is likely to cause a pinhole to be made.
(4) In the case where the underlayer of the alignment film is roughened to have convexed and concaved portions and the alignment state of the liquid crystal molecules is regulated by steps on a surface of the alignment film made by the convexed and concaved portions, the surface area of the underlayer on which the alignment film is formed is enlarged. This, together with the reason (2) above, is likely to cause a pinhole to be made.
When the pinhole is made for any of the above-described reasons, the image is not normally displayed at the site of the pinhole. This causes a problem that, for example, depending on the size or the position of the pinhole, the alignment film needs to be entirely peeled off and formed again, and as a result, the production cost is raised.
Patent Document 1 proposes a stamping technique of, after a pinhole is detected in an alignment film, transferring an alignment film repair agent to the pinhole. According to this stamping technique, a transfer head having the alignment film repair agent attached thereto is pressed to the pinhole to repair the alignment film. Therefore, the alignment film can be repaired easily, and the film thickness at the repaired site can be controlled easily.